Catalytic composition and process for the alkylation and transalkylation of aromatic hydrocarbons

ABSTRACT

Superior aromatic alkylation and transalkylation performance is obtained with a novel catalytic composition comprising a hydrogen form mordenite incorporated with alumina. The superior performance is a direct result of the catalyst composition having a surface area of at least 580 m 2  /g. A novel method of preparing a catalyst having a surface area of at least 580 m 2  /g is characterized by contacting a formed catalytic composite with an acidic aqueous solution.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of prior copendingapplication Ser. No. 124,147, filed Nov. 23, 1987, which is acontinuation-in-part of prior copending application Ser. No. 932,113filed Nov. 18, 1986, now U.S. Pat. No. 4,735,929, which is acontinuation-in-part of application Sr. No. 772,099, filed Sept. 3,1985, now abandoned, the contents of which are incorporated herein byreference thereto.

BACKGROUND OF THE INVENTION

The present inventionis related to an improved catalytic composition andan alkylation or transalkylation process employing that catalyticcomposition. More particularly, this invention involves an alkylation ortransalkylation catalyst compositio comprising a hydrogen formcrystalline aluminosilicate zeolite and a refractory inorganic oxide.

The alkylationo or transalkylation of aromatics are processes well knownfor their ability to produce such monoalkylaromatic products asethylbenzene, cumene, linear alkylbenzenes, and so forth. Suchmonoalkylaromatic compounds are important chemical precursors in theproduction of detergents and polymers among others. Alkylation catalyststhat are known to produce alkylaromatic compounds include the well-knownFriedel-Crafts catalysts: sulfuric acid, phosphoric acid, hydrofluoricacid, and aluminum chloride in either liquid or solid supported form.Solid granular catalysts such as clays, zeolites, and amorphousmaterials have also been utilized as aklylating reactants in bothamodified and naturally occurring form.

A myriad of processing schemes employing an alkylation reaction zoneand/or a transalkylation reaction zone are well known to producemonoalkylaromatic products in high yeilds. One drawback concernignexisiting alkylation/transalkylation processes is the potential for thealkylation and/or the transalkylation catalyst to produce undesirableproducts such as aklylating agent oligomers, heavy polyaromaticcompounds, and unwanted monoalkylaromatics. THe alkylating agentoligomers can be especially troublesome as they are often recovered withteh desired monoalkylaromatic product where they can detrimentallyaffect the utility of the monoalkylaromatic product in furtherconversion processes. An example of this would be the contaimination ofcumene with propylene oligomers which may reduce the utility of usingsuch contaminated cumene as a phenol process feedstock and ultimatelyfor the production of phenolic resins due to the presence of theoligomers as an inert compound within the cross-linked resins.

Another drawback inherent to some existing alkylation/transalkylationreaction zone containing processes is the use of Friedel-Craftscatalysts such as solid phosphoric acid or hydrofluioric acid as thealkylation and/or transalkylation catalysts. Many of these catalystsrequire a water cofeed and produce an extremely corrosive sludgeby-product. The utilization of such sludge-producing catalysts in analkylation process requires that special design consideratios be maderegarding unit metallurgy, safety, and by-product neutralization. Suchdesign considerationsa re typically costly and may add signaificantly tothe construction and operations costs of such processes. Additioally,the use of Friedel-Crafts catalysts requres a once-through processingscheme to ensure that damaging corrosive materials are not recycled intothe reaction zone. This requirement necessitates the opeation of theprocess at high conversion conditions which tend to produce greateramounts of unwanted by-products such as alkylating agent oligomers andheavy by-products.

More recently, crystalline aluminosilicate zeolites which have showncatalytic activity have been effecdtively used in the alkylation andtransalkylation of aromatics. Both antural and synthetic crystallinealuminosilicates have been employed. Included among these are the Type xand Type Y zeolites as well as synthetic mordenite.

Specifically, the zeolites known as mordenties have received greatattention. Mordenites are crystalline natureal or synthetic zeolites ofthe aluminosilicate type; generally, they ahve a composition expressedin moles of oxide of

1.0±0.2Na₂ O·Al₂ O₃ ·10±0.5SiO₂ ;

the quantity of SiO₂ may also be larger. Instead of all or part of thesodium, other alkali metals and/or alkaline earth metals may be present.

In general, it has been found that teh sodium form of mordentie is notparticularly effective for the alkylation or transalkylation ofhydrocarbons and that replacing all, or for the greater part, of thesodium cations with hydrogen ions yields the more advantageous hydrogenfrom mordenite. Conversion of the sodium form to the hydrogen form canbe accomplished by a number of means. One method is the directreplafement of soldium ions with hydrogen ions using an acidifiedaqueous solution where the process of ion exchange is employed. Anothermethod involves substitution of hte sodium ions with ammonium ionsfollowed by decompositin of the ammonium form using a high temperataureoxidative treatment.

The avticvity and selectivity of alkylation or transalkylation catalystsdepend on a variety of factors, such as the mode of catalystpreparation, the present or absence of promoters, quality of rawmaterials, feedstock quality, process conditions, and the like. Suitablecatalysts canb e conventionally prepared by combining commerciallyavailable crystalline zeolites, such as, a hydrogen form mordenite, witha suitable mtric material. A new catalyst has now been discovered whichexhibits greatly improved alkylation and transalkylation performancewhen compared to conventionally prepared catalysts.

OBJECTS AND EMBODIMENTS

Accordingly, there is provided a catalyst cmposition for the alkylationand transalkylation of aromatic hydrocarbons, which comprises a hydrogenform mordenite, and from about 5 to 25 wt.% alumina. The support iscontacted with an acidic aqueous solution after it is formed. teh acidiccontacting occurs at conditions selection to increase the surface areaof the composite to at leat 380 m² /g without increasing thesilica/alumina ratio of the mordenite.

In another aspect, the inventio s amethod of manufacturing theaforementioned catalyst composition. Manufacturing of the catalystcomprises forming a composite comprising hydrogen form mordenite andfrom about 5 to 25 wt.% alumina, thereafter contacting formed compositewith an acidic aqueous solutin under conditions selected to increase thesurface area of teh composite to at least 580 m² /g without increasingthe silica/alumina ratio of the mordenite.

In another aspect, the invention is a process for alkylating ortransalkylating an aromatic hydrocarbon by contacting a feedstockcomprising an aromatic substrate and an alkylating agent or in teh caseof transalkylation with a transalkylatable aromatic hydrocarbon in areaction zone with the catalyst composition described above.

These, as well as other embodiments of the present invention, willbecome evident from teh following, more detailed description.

INFORMATION DISCLOSURE

The prior art recognizes a myriad of catalyst formulatios for thealkylation or transalkylation of hydrocarbons. It is well known thatcids, such as strong mineral acids, can be used to modify crystallinealuminosilicate zeolite powders through decationization anddealumination. Ammonium compounds have also been successfully employedto convert crystalline aluminosilicates from alkali and/or alkalinemetal cation form to the hydrogen form. Combinatios of zeolite andrefractory inorganic oxide have been disclosed, however, the art issilent as to the inherent problem of loss of the zeolite surface area asa result of dilution and forming techniques associated wtih therefractory inorganic oxide.

Combinations of the acid and ammonium treatments have been disclosed foruse on aluminosilicate powders. U.S. Pat. No. 3,475,345 (Benesi)discloses a method of converting aluminosilicate zeolites, particularlya sodium form synthetic mordenite, to the hydrogen form utilizing athress-step pretreatment performed ont eh powdered zeolite. THesepretreatment steps consist of: (1) a hot acid treatment, (2) a cold acidtreatment, and (3) treatment with an ammonoium compound. U.S. Pat. No.3,442,794 (Van Helden et al) also disclsoes a method for thepretreatment of aluminosilicate zeolites to the hydrogen form. Again,the preferred zeiolit is the synthetic sodium form of mordenite. Themethod disclsoed is very similar to U.S. Pat. No. 3,475,345 mentionedabove, with the distinguishing feature being a separatly performedtwo-step pretreatment with (1) an acid compound and (2) an ammoniumcompound in arbitrary order. An important feature of both references isthat the treatments are performed solely on teh aluminosilicate zeolitewith tehe xpress intention of modifying said zeolite before beingutilized in a catalyst formulation and that no mentionof hte importanceof the surface area of the catalytic composite is disclosed. This isdistinguished from the present invention in that any treatment performedis subsequent to the zeolite being incorporated into a formed catalystcomposite and more importantly without any apparent modification of thezeolite itself.

Treatment of the aluminosilicates with acid have not only been means forincreasing the silica to alumina ratio. Typically, a silical to aluminaratio of about 10:1 is observed for a sodium form synthetic mordeniteand is substantially unchanged if an ammonium treatment is used toconvert the modenite to the hydrogen form. If a mordenite powder issubjected to an acid treatment as taught in U.S. Pat. No. 3,597,155(Flanigen), an increase in the silica to alumina ratio is effected. Theacid treatment is believed to cause a reduction of the frameworktetrahedra aluminum atoms, thus increasing the proportion of siliconatoms present in teh zeolitic structure.

Transalkylation performance is enhanced when the silica to alumina raitoof a mordenite powder is increased. U.S. Pat. No. 3,551,510 (Pollitzeret al) teaches the use of a hot hydrochloric acid extracted mordenitecatalyst in a transalkylation reacion zone. Again, this referencespecifically teaches of the use of acid treatment on the zeolite powderalone for the puroose of increasing the silica to alumina ratio, whereasthe subject invention incorporates an already high silica to aluminaratio crystailline aluminosilicate into the catalytic compsote andpost-treats with acid to clean out teh catalyst pors and therebyincrease the surface area of the ctalyst. These referencs also do notteach the importance of the surface area of the catalystic compositie orits relationship to aromatic alkylation or transalkylation performance.

A commone attribute of the above-mentioned prior art is that, in allcases, the crystalline aluminosilicate alone, in particular thesynthetic sodium form of mordenite, is subjected to an acid and/or anammonium pretreatment step(s) to modify the aluminosilicate before itsincorporation into the catalyst composition. Although the pretreatmentof the mordenite as described in the above references enhances theperformance of catalytic composites comprising such pretreatedmordenite, further improvements of still obtainable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of the diisopropylbenzene (DIPB) conversion in percentexpressed alternatively as: ##EQU1## plotted against hours on-stream.

FIG. 2 is a plot of benzene conversion in percent plotted against hourson-stream where benzene conversion may be expressed as: ##EQU2##

DETAILED DESCRIPTION

While previous work dealt exclusively with pretreatment of thealuminosilicate component of a catalyst, it is one of hte objects of thepresent inventio to provide a novel catalyst composition which ischaracterized by exceptionally high surface area and which exhibitsimproved alkylation and transalkylation performance.

According to the present invention, there is provided a catalystcomposition fo rthe alkylation or transalkylation of aromatichydrocarbons. THe catalyst composition of the present inventio comprisesa hydrogen form mordenite and from about 0.5 to 50 wt.% alumina, andpreferably 5 to 25 wt.% alumina with said catalyst composition having asurface area of at leat 580 m² /g. We have found that significantimprovements in alkylation and transalkylation performance are realizedwith the surface area of the catalyst composition is at or above 580 m²/g. Although a maximum surface area of the catalyst composition has notbeen determined experimentally, it is believed that an upper limie of700 m² /g is possible. Obtaining such a high surface area in the rangefrom about 580 to 700 m² /g is the object of one of the embodiments ofthe subject invention and is further illustrated ins ubsequent examples.

An essential component of the instant invention is the hydrogen formmordenite. While mordenite is naturally occurring, a variety ofsynthetic mordenites are available commercially, usually in a powderform. These synthetic mordenites can be obtained in both the sodium formand hydrogen form and at varied silica to alumina ratios. It is apreferred embodiment of the present invention that the mordenite be ofthe hydrogen form and that teh silica to alumina ratio be at leat 16:1,more specifically, in the range from 16:1 to 60:1. The pretreatmentstops taught in the aforementioned references are routinely andtypically employed in the manufactured of commercially availablemordenite powders which meet the requirements as a starting materials asset forth in the present invention. These pretreatment steps are used toincrease the silica to alumina ratio of hte mordenite zeolite and toconvert the sodium form to the more desirable hydrogen form.

The hydrogen form mordenite is incorporated with alumina and formed into acatalytic composite. The formed catalytic composite may be preparedby any known method in the art including the well-known oil drop andextrusion methods. THe hydrogen form mordenite may be present in anamount within the range of 50 to about 99.5 wt.%, preferably with thecommercially desirable range of 75 to about 95 wt.%. Thus, the aluminalis preferably present in an amount within the rnage of from about 5 toabout 25 wt.%, based on total weight of the catalyst composition.

The preferred alumina for use in the present invention is selected fromthe group consisting of gamma-alumina, eta-alumina, and mixturesthereof. Most preferred is gamma-alumina. Other refractory inorgaincoxides which may be used include, for example, silical gel,silica-alumina, magnesia-alumina, zirconia alumina,phosphrous-containing alumina, and the like.

Surprisingly and unexpectedly, it has been found that a catalystcomposition prepared in accordance with and containing the components asclaimed in teh inventio will possess a surface area higher than anycatalyst heretofore described in the art. This high surfasce area of atleast 580 m² /g is surprising when one considers not only the dilutingaffect of an alumina support material having relatively low surfce area(maximum approximately 250 m² /g), but also considering the lowering ofsurface area caused by the particular forming technique employed. Aexemplified herein below, catalyst of the prior art do not obtain thehigh surface area of the instant catalyst and thus demonstrate inferiorperformance, particularly as alkylation and transalkylation catalysts.THe prior art does not teach or suggest how to obtain amordenite/alumina catalyst having a surface area of at least 580 m² /g.Surface area, as referred to herein, is determined by employing theLangmuir method of correlating adsorption/desorption isotherm data. THeLangmuir method is especially suitable for catalytic compositescontainign high percentages of crystalline aluminosilicates. The dataneeded for the Langmuir method is typically obtained by well knownadsorption/desorption apparatuses, preferably a nitrogenadsorption/desorption apparatus. THerefore, the present inventio allowsfor a catalyst composition using a high surface area mordenite withoutloss of this surfasce area when formed with alumina to geivecommercially acceptable formulation. Likewise, the benefit of thepresence of alumina, which imparts, among other things, strength to thecatalyst composition, may be achieved without penalty with regard to thesurface area of the mordenite.

Any method may be employed which results in a final catalyst compositehaving atleast a surface area of 580 m² /g. Catalyst compositions withhigh surface areas can be arrived at in anumber of ways, such as, usinga hudrogen form mordenite powder which inherently has a very highsurface area, or by having one component of the composite, which has ahigh surface area, in great proportion to other components. A preferredmethod of achieving a surface area of at least 580 m² /g is to contactthe formed catalytic composite with an acidic aqueous solution. Thisacidic aqueous solution may contain ammonium ions. the formed catalystcomposite may be dried and/or calcined prior to its contact with theaqueous solution.

The acidic nature of the aqueous solution is attained by employing anacid. Particularly suitable are strong mineral acids such as H₃ PO₄, H₂SO₄, HNO₃, and HC1. HC1 is the preferred acid of the present invention.Of course, it is contemplated that mixtures of various acids may also beemployed. If the acidic aqueous solution contains ammonium ions, thepreferred source of these ions is NH₄ C1, but any ammonium compoundwhich can form ammonium ions, such as NH₄ OH, NH₄ NO₃, NH₄ sulfates, NH₄phosphates and the like, should be suitable.

Concentrations of the acid and ammonium ions in the aqueous solutiona renot critical and can bary from 0.5 M to 6 M for the acid concentrationand 0.5 M to 4 M for the ammonium ion concentration. Particularly goodresults are obtained using a solution containing acid and ammonium ionconcentratios within the range of 2 to 5 M for the acid and 1 to 3 M forthe ammonium ion.

A plurality of methods for contacting the formed catalytic composite andthe acidic aqueous solution is envisioned with no one method ofpaticular advantage. Such contacting methods may include, for example, astationary catalyst bed ina static colution, a stationary catalyst bedin an agitated solution, a stationary catalyst bed in a continuouslyflowing solution, or any other means which efficiently contacts thecatalyst composition with the acidic aqueous solution.

The temperature of the contacting solution should be within the range of25° C. to about 100° C., preferably within the range of from abut 50° C.to about 98° C. The time required for the contacting step will dependupon concentrations, temperature and contacting efficiency. In generaly,the contacting time should be at least 0.5 hour, but not more than 4hours, prferably between 1 and 3 hours in duration.

As a result of contacting the formed catalytic composite with the acidicaqueous solution, an increase in the measured surface area is observed.Surprisingly and unexpectedly, this increase in surface area, to 580 m²/g or higher, is not accompanied by an icrease in teh silica to aluminaratio of the hydrogen form crystalline aluminosilicate as measured byMagic Angle Spinning NMR (MASNMR). The MASNMR technique, which is wellknown analytical method of the art, indicates no reduction in theframework tetrahedral aluminum atoms of catalyst compositionso f thepresent invention. Although it is not certain the exact reason why thesurface area is higher after contacting the formed catalytic composite,it is believed that the acidic aqueous solution is removing occludedions from the mordenite which are deposited therein as a result of theforming technique employed.

The catalyst of the instant invention has particular utility in thealkylation or transalkylation of aromatic hydrocarbons.

In the alkylation of an aromatic substrate with an alkylating agent in aprocess utilizing the catalyst compositoin of this invention, thealkylating agent which may be charged tohe alkylation rection zone maybe selected from a group of diverse materials including monoolefins,diolefins, polyolefins, acetylenic hydrocarbons, and also alkylhalides,alcohols, ethers, esters, the later including the alkylsulfactes,alkylphosphats and various esters of carboxylic acids. TH preferredolefin-acting compounds are olefinic hydrocarbons which comprosemonoolefins containing one double bond per molecule. Monoolefins whichmay be utilized as olefin-acting compounds in the process of the presentinvention are either normally gaseous or normally liquid and includeethylene, propylene, 1-butene, 2-butene, isobutylene, and the highermolecular weight normally liquid olefins such as the various pentenes,hexenes, heptenes, octenes, and mixtures thereof, and still highermolecular weight liquidolefins, the latter including various olefinpolymers having from about 9 to about 18 carbon atoms per moleculeincluding propylene trimer, propylene tetramer, propylene pentamer, etc.C₉ -C₁₈ normal olefins may be used as may cycloolefins such ascyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, etc.may also be utilized, although not necessarily with equivalent results.

It is a preferred embodiment of th present ivnntion that the monoolefincontains at leat 2 and not more than 14 carbon atoms. More specifically,ti si preferred that the monoolefin is prpylene.

The aromatic substrate component of the alkylation process of thisinvention which is charged ot the alkylation reaction zone in admixturewith the alkylating agent mayb e selected from a group of aromaticcompounds which include individually and inadmixture with benzene andmonocyclic alkylsubstituted benzene having the structure: ##STR1## whereR is a hydrocarbon containing 1 to 14 carbon atoms, and n is an integerfrom 1 to 5. In other words, the aromatic substrate portion of thefeedstock may be benzene, benzene containing from 1 to 5 methyl and/orethyl group substituents, and mixtures thereof. Non-limiting examples ofsuch feedstock compounds include benzene, toluene, xylene, ethylbenzene,mesitylene (1,3,5-trimethylbenzene), cumene, n-propylbenzene,butylbenzene, dodecylbenzene, tetradecylbenzene, and mixtures thereof.It is specifically preferred that hte aromatic substrate is benzene.

In a continuous process for alkylating aromatic hydrocarbons witholefins, the previously described reactants are continuously fed into apressure vessel containing the above-described catalyst. TEh feedadmixture may be introduced into the alkylation reaction zone containingth alkylation catalyst at a constant rate, or alternataively, at avariable rate. Normally, the aromatic substrate and olefinic alkylatingagent are contacted at a molar ratio of from about 1:1 to 20:1 andpreferably from about 2:1 to 8:1. The preferred molar feed ratios helpto maximize the catalyst life cycle by minimizing the deactivation ofthe catalyst by coke and heavy material deposition upon the catalyst.The catalyst may be contained in one bed within a reactor vesel ordivided up among a plurality of beds within a reactor. THE alkylationreaction system may contain one or more reaction vessels in series. THefeed to the reaction zone can flow vertically upwards, or downwardsthrough the catalyst bed in a typical plug flow reactor, or horizontallyacross the catalyst bed in a radial flow type reactor.

Temperatures which re suitable for use in the alkylation process hereinare those temperatures which initiate a reaction between an aromaticsubstrate and the particular olefin used to selectively produce thedesired product. Generally, temperatures suitable for use are from about100° to about 390° C., especially from about 150° to about 275° C.Pressures which are suitable for use herein preferably are above about 1atmosphere but should not be in excess of about 130 atmopheres. Anespecially desireable pressure range is from about 10 to abut 40atmospheres; with a liquid hourly space velocity (LHSV) based upon thearomatic substrate feed rate of from about 0.5 to about 50 hr⁻¹, andespecially from about 2 to about 10 hr⁻¹. It should be noted that thetemperature and pressure combination used herein is to be such that thealkylation reaction takes place in essentially the liquid phase. In aliquid phase process for producing alkylated aromatics, the catalyst iscontinuously washed with reactants, thus preventing buildup of cokeprecursors on the catalyst. This results in reduced amounts of carbonforming on said catalyst in which case catalyst cycle life is extendedas compared to a as phase alkylation process in whichcoke formation andcatalyst deactivation is a major problem. To further reduce the rate ofcatalyst deactivation, it is contemplated that H₂ may be added to thealkylation reacation zone feed in an amount sufficient to saturate therespective reaction zone liquid feed. The addition of H₂ in equilibriumamounts to the rspective liquid phase feed streams helps to reduce thecatalyst deactivation rate by inhibiting the polymerization potential ofpore blocking polymerizable compounds produced by the process.

The products of the alkylation reaction or transalkylation reaction shereinbelow described may be recovered using techniques known in theprior art. Examples of some of the separation techniques that could beemployed alone or in combination to recover alkylation rection zoneproducts are: distillation including vacuum, atmospheric, andsuperatmospheric distillation; extractiont echniques including, forexample, liquid/liquid extractions, vapor/liquid extractions,supercritical extractions and others; absorption techniques, adsorptiontechniques, and any other known mass transfer techniques which canachieve the recovery of the desired separation zone products inessentially pure fractions. TEh separation processes mentioned above areincluded as examples of the many techniques which could be utilized toachieve the necessary separation, purification, and recovery of thealkylation reaction zone products. Hence, separation zone processingconditions are not disclosed as they will depend upon the choice of hteseparation techniques employed and further upon the reactants used andthe configuration of the separation zone equipment. It is expected thatcontinuous distillation will be the primary separation technique used.THe optimal distillatio conditins willa gain depend upon teh exactscheme chosen to achieve the desired separation.

The catalyst of this invention is also useful in the transalkylation oftransalkylatable aromatics. THe transalkylation process of thisinvention preferably accepts as feed a transalkylatable hydrocarbonsuseful in the transalkylation processa re comprised of aromaticcompounds which are charcterized as consitiuting an aromatic substratebased molecule with one or more alkylating agent compounds taking theplace of one or more hydrogen atoms around the aromatic substrate ringstructure. THe alkylating agent compounds identified above are identicalto those described as useful in the alkylation processa bove andpreferably C₂ -C₁₄ aliphatic hydrocarbons.

The aromatic substrate useful as a portion of the feed to thetransalkylation process is the same as that descibed above as useful inthe alkylation process employing the instant catalyst.

The transalkylation process of this invention may have a number ofpurposes. In one, the catalyst of hte translkylation rection zone isutilized to remove the alkylating agent compounds in excess of one fromthe ring structure of polyalkylated aromatic compounds and to transferthe alkylating agent compound to an aromatic substrate molecule that hasnot been previously alkylated, thus increaseing the amount of thedesired aromatic compounds produced by the process. In a relatedpurpose, thereaction performed in the transalkylation reaction zoneinvolves the removal of all alkylating agent components fromasubstituted aromataic compound and in doing so, converting the aromaticsubstrate into benzene.

To transalkylate polyalkylaromataics with an aromatic substrate, a feedmixture containing an aromatic substrate and polyalkylated aromaticcompounds in mole ratios ranging from 1:1 to 50:1 and preferably from4:1 to 10:1 are continuously or intermittently introduced into atransalkylation reaction zone containing the catalyst of this ivnentionat transalkylation conditions including a temperature from about 100° toabout 390° C., and especially from about 125° to about 275° C. Pressureswhich are suitable for use herein preferably are above 1 atmosphere butshould not be in excess of about 130 atmospheres. An especiallydesirable pressure range is from about 10 to abut 40 atmospheres. Aliquid hourly space velocity (LHSV) of from about 0.1 to about 50 hr⁻¹,and especially from about 0.5 to about 5 hr-1 based upon the combinedaromatic substrate and polyalkylaromatic feed rate is desirable. Whilethe process of the instant invention may be performed int eh vaporpahse, it should be noted that the temperature and pressure combinationutilized in the transalkylation reaction zone is preferred to be suchthat the transalkylation reactions take place in essentially the liquidphase. In a liquid phase transalkylation process for producingmonoalkylatomatics, the catalyst is continuously washed with rectants,thus preventing buildup of coke precursors on the catalyst. This resultsin reduced amounts of carbon forming ons aid catalyst in whcih casecatalyst cycle life is extended as compared to a gas phasetransalkylation process in whichc oke formation and catalystdeactivation s a mojor problem. Additionally, the selectively tomonoalkylaromatic production, especially cumene production, is higher inthe catalytic liquid phase transalkylation reaction herein as comparedto catalytic gas phse transalkylation reaction.

The following examples are presented for purposes of illustration onlyand are not intended to limit the scope of the present invention.

EXAMPLES

A number of experiments were conducted to study how changes in thesurface area of alkylation or transalkylation catalyst compositiesaffect process performance. Three catalysts were prepared forevaluation. In all the catalyst preparations described in teh followingexamples, the starting material was the hydrogen form, low sodium,partially dealuminated syntheitic mordenite powder (marketed by UnionCarbide under the name LZ-M-8), hereinafter referred to as theas-recevied mordenite.

EXAMPLE I

Experiments were undertaken to study the performance of two catalyticcomposites in promoting alkylationa nd transalkylation reactions.

CAtalyst A was formulated by amethod inconsistent with that of thealkylation or transalkylation catalyst of the present ivnention. Theas-received mordenite powder was mixed with an alumina powder to aweight ratio of 9:1, followed by the addition of an acidifiedpeptization solution. The admixture was then extruded by means known inthe art. After the extrusion process, the extrudate was dried andcalcined. the resulting surface area of this catalyst was 540 m² /g.

EXAMPLE II

The catalyst base formulation used for Catalyst B is identical to thatused for Catalyst A of Example I. THe difference arises in the stepsfollowing the drying and calcination of the acid peptizedsilica/mordenite extrudate. Following the drying and calcination steps,the extrudate was exposed to an aqueous solution comprising 10 wt.% HCIand 10 wt.% NH₄ CI at 60° C. for 150 minutes at a solutin to zeolitevolumetric ratio of 5:1. After the acid was step, the catalyst was againdried and calcined. Catalyst B is the acid-washed catalyst of thepresent invention. THe resulting surfasce area of this catalyst was 620m² /g.

EXAMPLE III

Catalyst C was formulated by amethod inconsistent with that of thecatalyst of the present invention. To prepare CAtalyst C, a mixture of50 wt.% mordenite powder and 50 wt.% alumina powder was combined with a5.5 wt.% nitric acid solution. THe resultingdough was extruded by meansknown in the art. Teh extrudate was calcined at 150° C. for 1 hour andthen at 480° C. for 3 hours. THe calcined extrudate was next contactedwith a 15 wt.% solution of ammonia for 1 hour and then dried. The dried,finished extrudate was calcined at 150° C. for 1 hour and 480° C. for 2hours. tEh finished catalyst has a surface area of 450 m² /g.

EXAMPLE IV

Catalysts B and C as described in the previous examples were evaluatedfor aromatic alkylation performance in a flow-through reactor containing20 cc of catalyst by processing a feed comprising a mixture of benzeneand propylaene at a 4:1 molar ratio. Conventional product recovery andanalysis techniques were used to evaluate the catalyst performance ineach case.

The operating conditions used to evaluate the alkylation performance ofthe three catalysts omprised a rector pressure of 34 atmospheres,aliquid hourly spce velocity of 4 hr⁻¹ based upon teh benzene feed rate,and a maximum temperature of 200° C. No recycle of the reactor effluentto the reactor inlet was employed in this testing. THe results of thepilot plant tests can be found in Table 1 below.

                  TABLE 1                                                         ______________________________________                                                       Alkylation Reaction Selectivities                                               Catalyst B                                                                              Catalyst C                                         Yields (mole %)  200° C.                                                                          200° C.                                     ______________________________________                                        Cumene           85.9      82.6                                               Diisopropylbenzenes                                                                            12.2      16.1                                               para             4.4       5.9                                                meta             7.7       10.2                                               ortho            0.1       --                                                 ______________________________________                                    

The pilot plant test indicate that Catalyst B, the alkylation catalystof the present invention produces an alkylation product which comprises98.1 mole % isopropylbenzene compounds of which 85.9 wt.% is themonoalkylaromatic cumene. Catalyst C, the low mordenite/low surface areacatalyst of the prior art produces an alkylate with 82.6 mole % of themonoalkylaromataic cumene. THe only difference in prepartaion of the twocatalyst was that Catalyst B of the isntant invention was treated withacid after forming which resulted in an increase int eh surface area ofthe catalyst.

Thus, it can be concluded that the catlyst of the instant invention ismore useful in the production of monoalkylaromatics in an aromaticalkylation process directed twoard the production of such products thanthe non-acid washed catalyst of the prior art. EXAMPLE V

Catalyst B, the transalkylation catalyst of the present invention, wastested at transalkylation reaction conditons along with CAtalyst A, anon-acid washed mordenite catalyst , and Catalyst C, a low surface areamordenite catalyst, both not catalysts of th presen tinvention. THecatalysts were evaluated in a pilot plant consisting of a tubularreactor holding 50 cc of transalkylation catalyst and a product recoveryzone. To the reactor was fed a liquid feed blend comprised of 7.2 molesof benzene, 1 mole of diisopropylbenzene, and 0.25 moles of otheralkylabenzenes at a total liquid hourly space velocity (LHSV) of 1.3hr⁻¹. The reactor pressure was operated at 34 atmospheres, and thereaction temperature was hels at 150° C. maximum. The results of thepilot plant tests are presented in FIGS. 1 and 2. IT is evident fromfgiure 1 that the diisopropylbenzene conversion capability of CAtalystB, the transalkylation catalyst of hte instant invention, is much higherthan that of the two catalyst not of the instant ivnetnion. The abilityof all three catalysts to promote the rection fo benzene withpolyalkylated aromatics as seen inFgiure 2 is similar in all cases. Thisleads to the conclusion that Catalyst B, the acidashed high surface areatransalkylation of diisopropylbenzene with benzene to produce cumene ata high siisopropylbenze conversion than a non-acid washed or lowsurfasce area mordenite containing catalyst. This is evidence asmentioned by the ability of Catalyst B to utilize an amount of benzenesimilar to Catalysts A and C to produce a greater amount of isopropylbenzenes.

What is claimed is:
 1. A process for the alkylation of aromatics which comprises passing a feed stream comprising ana lkylating agent adna naromatic substrate into an alkylationr eaction zone containing an alkylation catalyst, at alkylation reaction conditions and ecovering the alkylation reaction product where the alkylationcatalyst comprises a hyrogen form mordenite dispersed in an alumina matrix, said catalyst cmprising from about 5 to 25 percent by weight of alumina, and werein said catalyst is contacted with an acidic aqueous solution after it is formed, said contacting occurring at conditions selected to icnrease the surface area of the catalyst to at least 580 m² /g without increasing the silica/alumina ration of the mordenite.
 2. The process of claiam 1 further characterized in that the alkylation catalyst is spherical, cylindrical, or granular in shape.
 3. The process of claim 1 further characterized in that the alumina is selected from the group consisting of gamma-alumina, eta-alumina, and mixtures thereof.
 4. THe process of claim 1 further characterized in that the alkylating agent is selected from the grup consisting of an alkene, an alcohol, an alkylhalide, an alkylsulfonate, or mixtures thereof.
 5. The process of claim 1 further characterized in that the alkylating agent is a monoolefin and has a carbon number from 2 to
 14. 6. The process of claim 1 further characterized in that the aromatic substrate is benzene.
 7. The process fo claim 1 further characterized in that teh alkylation rection conditions comprise a temperature of from 100-390° C., a pressure of from 1-130 atmospheres, a liquid hourly space velocity of from 0.5 to 50 hr⁻¹, and an aromatic substrate to alkylating agent feed ratio of from 1:1 to 20:1. 